Time-integrated sampler of bodily fluid

Abstract

An apparatus and corresponding method obtains time-integrated samples of fluid from the rumens of cattle, sheep, goats or other animals through a cannula. The apparatus allows ruminal fluid to be sampled under standard conditions. It reduces the labor required to obtain samples and allows dynamic fermentation patterns to be followed. The apparatus includes a ceramic filter connected to a sampling tube assembly. The filter is placed in the rumen and vented to atmosphere by a first tube. A second tube connects an inside region of the filter to a peristaltic pump which removes fluid for time-integrated sampling.

The invention claimed is:  
     
       1. A system for sampling bodily fluid in an animal's body, comprising: 
       a collection vessel;  
       a cup-shaped ceramic filter adapted to be placed at a sampling site within the body of the animal;  
       an inner tube flow-connected to a collection region within said ceramic filter at one end and adapted to extend out of the animal's body to a second end;  
       an outer tube coaxially surrounding said inner tube and having a first open end adjacent said ceramic filter and a second end adapted to extend to an outside of the animal's body; and  
       a peristaltic pump having an inlet connected to said inner tube and an outlet connectable to said collection vessel.  
     
     
       2. The system according to  claim 1 , further comprising an outer surrounding conduit surrounding said outer tube and adapted to extend from adjacent said ceramic filter to outside of the animal body, said outer conduit adapted to extend through a cannula formed through the animal body, said outer conduit attached to a cannula cover which closes said cannula. 
     
     
       3. The system according to  claim 1 , wherein said filter comprises a wall thickness of about 0.2 centimeters. 
     
     
       4. The system according to  claim 1 , wherein said filter comprises a pore size of about 6 micrometers. 
     
     
       5. A method for sampling bodily fluid in an animal's body comprising the steps of: 
       providing a filter element having a filtering wall in fluid communication with an internal void;  
       connecting the filter element to a tube for removing fluid collected in said filter element;  
       inserting the filter element at a sampling site within the body of the animal and collecting fluid passing through the filtering wall within the internal void of the filter element; and  
       removing fluid collected in said internal void by a pump while maintaining pressure within the internal void at near atmospheric pressure.  
     
     
       6. The method according to  claim 5 , wherein said step of removing fluid is further defined in that a second tube is connected to said filter element, said second tube exposing an inside of said filter element to atmospheric air from outside said animal's body. 
     
     
       7. A sampling apparatus for sampling fluids inside an animal's body comprising: 
       a peristaltic pump;  
       a filter element adapted to be placed inside the body of the animal and comprising a filtering media defining an outside surface and an inside surface that defines an enclosed volume;  
       a first tube flow-connected to said enclosed volume at one end and open at an opposite end; and  
       a second tube flow-connected to said enclosed volume at one end and to a suction of said peristaltic pump at an opposite end.  
     
     
       8. The sampling apparatus according to  claim 7 , wherein said second tube has a smaller diameter than said first tube and is fit coaxially within said first tube. 
     
     
       9. The sampling apparatus according to  claim 7  further comprising an outer conduit connected to said filter element at one end and connected to a cannula cover at a position on said outer conduit spaced from said filter element, said first and second tubes fit within said outer conduit. 
     
     
       10. The sampling apparatus according to  claim 7 , wherein said filter element comprises a filtering media wall thickness of about 0.2 centimeters. 
     
     
       11. The sampling apparatus according to  claim 7 , wherein said filter element filtering media comprises a pore size of about 6 micrometers. 
     
     
       12. A sampling apparatus for sampling fluids inside an animal's body comprising: 
       a peristaltic pump;  
       a filter element comprising a filtering media defining an outside surface and an inside surface that defines an enclosed volume;  
       a first tube flow-connected to said enclosed volume at one end and open at an opposite end;  
       a second tube flow-connected to said enclosed volume at one end and to said peristaltic pump at an opposite end; and  
       an outer conduit connected to said filter element at one end and connected to a cannula cover at a position on said outer conduit spaced from said filter element, said first and second tubes fit within said outer conduit.  
     
     
       13. A sampling apparatus for sampling fluids inside an animal's body, comprising: 
       a suction device having an inlet for drawing fluid;  
       a filter element adapted to be placed inside the body of the animal and having a porous filtering wall and an enclosed void at least partly defined by said porous filtering wall;  
       a first tube flow-connected to said void at one end and open at an opposite end, said tube adapted for said opposite end to be outside the body of the animal; and  
       a second tube flow-connected to said void at one end to said inlet of said suction device at an opposite end.  
     
     
       14. The sampling apparatus according to  claim 13 , wherein said suction device comprises a pump. 
     
     
       15. The sampling apparatus according to  claim 13 , wherein said filter element comprises a wall of porous material surrounding said internal void. 
     
     
       16. The sampling apparatus according to  claim 13 , wherein said second tube has a smaller diameter than said first tube and is fit coaxially within said first tube. 
     
     
       17. The sampling apparatus according to  claim 13 , further comprising an outer conduit connected to said filter element at one end and connected to a cannula cover at a position on said outer conduit spaced from said filter element, said first and second tubes fit within said outer conduit. 
     
     
       18. The sampling apparatus according to  claim 13 , wherein said suction device comprises a peristaltic pump; 
       wherein said filter element comprises a cup-shaped wall of porous materials surrounding said internal void;  
       wherein said second tube has a smaller diameter than said first tube and is fit coaxially within said first tube; and  
       further comprising an outer conduit and a cannula cover adapted to seal an opening to the body of the animal, said outer conduit connected to said filter element at one end and connected to said cannula cover at a position on said outer conduit spaced from said filter element, said first and second tubes fit within said outer conduit.  
     
     
       19. The sampling apparatus according to  claim 18 , wherein said filter element comprises a ceramic filter. 
     
     
       20. The sampling apparatus according to  claim 18 , wherein said filter element comprises a ceramic filter having a pore size of about 6 micrometers.